I have tried yesterday and the Aura (2.5.2) connected flawlessly with Calibre (0.9.30) so I was able to send books to the device. But since it's an out-of-the-box one, the database is in a pristine state. I hope Today's Calibre release will solved everything for you.

If memory serves, the previous Calibre version wasn't fully compatible with the Aura because Kovid was away for a week when the first Aura ereaders arrived. There was a two-week gap between Calibre's general update, David's plugin update and people starting to use the Aura.

Calibre 0.9.30 nis definitely compatible with all the Kobo devices running firmware 2.5.2. Some people have gone back to 0.9.29 because the extended driver has an issue when run with 0.9.30.

I think aceflor problem is something else. I have asked for more details in another thread.